*{
    /*清除内白边距*/
    margin: 0px;
    /*清除外边距*/
    padding: 0px;
    /*清除边框*/
    border: 0px;
    /*清除背景*/
    background:none;
}
div{
    /*自动居中*/
    margin: 0 auto;
}
.background_red{
    background-color: #FF0000;
}
.clear_ul{
    /*清除圆点*/
    list-style-type: none;
}
.color_red{
    color: red;
}
.border_red{
    border-style: solid;
    border: 2px;
    border-color: #FF0000;
}
.border_blue{
    border-style: solid;
    border: 2px;
    border-color: #00f7ff;
}
.yd{
    /*移动*/
    position: relative;
    top:22px;
    left: 22px;
}